Heat sealable regenerated cellulose films enabled by zein coating for sustainable food packaging

Abstract

The development of green packaging materials is requested due to the growing concerns about plastic waste. As the most abundant natural polymer on earth, cellulose can be dissolved and regenerated to make transparent films. However, cellulose is not a thermoplastic, so cellulose films are usually sealed by an adhesive for packaging applications. Herein, this study aimed to endow regenerated cellulose (RC) films with heat sealability by coating a layer of zein, and the mechanical and barrier properties of the composite cellulose/zein films were characterized. The results revealed that, with a thin zein coating, all the composite films were able to be sealed by a tabletop impulse sealer without the need for high temperature or high pressure and showed larger tensile strain and better water vapor and oxygen barrier properties compared to the RC films. Moreover, it was worth noting that the blueberries packed in the heat-sealed cellulose/zein bags were protected from oxidation and spoilage during a 12-day storage period and were comparable to the ones packed by Ziploc®. Thus, this work demonstrates a facile way to fabricate cellulose-based packaging materials that are heat sealable and have potential applications in sustainable food packaging.